During normal use, contact lenses become soiled or contaminated with a wide variety of compounds that can degrade lens performance. For example, a contact lens will become soiled with biological materials such as proteins or lipids that are present in the tear fluid and which adhere to the lens surface. Also, by handling of the contact lens, sebum (skin oil) or cosmetics or other materials can soil the contact lens. These biological and external contaminants can affect visual acuity and patient comfort. Accordingly, it is important to remove any debris from the lens surface for continued comfortable use with a lens care solution that contains one or more cleaning components.
Contact lens care solutions must also contain one or more antimicrobial components. Presently, the two most popular antimicrobial components are poly(hexamethylene biguanide), at times referred to as PHMB or PAPB, and polyquaternium-1. PHMB-based care solutions represent a significant improvement in patient comfort and antimicrobial effectiveness compared to most other antimicrobial components. However, as with any antimicrobial component there remains a tradeoff between the concentration of the antimicrobial component in the solution and the comfort experienced by the patient. Due to its wide commercial acceptance, extensive efforts have been directed to improve the antimicrobial efficacy or the comfort level to the patient by chemically modifying PHMB.
Those of ordinary skill in the art are also looking to other classes of antimicrobial compounds that could possibly improve upon the present PHMB-based or polyquaternium-1-based lens care solutions. Such compounds could possibly replace PHMB or polyquaternium-1 in the solutions. Alternatively, the compounds could be added to PHMB and polyquaternium-1 solutions to enhance the biocidal activity of the solutions.
Accordingly, this may allow one to formulate a lens care solution with relatively less amounts of PHMB or polyquaternium-1, and possibly improve upon other desired features such as greater comfort.
U.S. Pat. No. 7,192,937 describes ophthalmic compositions containing one or more oligosaccharides in an amount effective to disinfect or preserve contact lenses, as a rewet drop for contact lenses or to preserve pharmaceutical formulations. A particular oligosaccharide described in U.S. Pat. No. 7,192,937 is stearyl dihydroxypropyldimonoim oligiosaccharide (SDO) of general formula

SDO is sold under the tradename Oligioquat® M and is available from Arch Chemicals, S. Plainfield, N.J., and has a reported weight average molecular weight of 25 k to 50 k. The compositions also include an aminoalcohol buffer and a tonicity agent.
U.S. Pat. No. 6,277,365 describes ophthalmic compositions containing one or more ethoxylated glycosides with a quaternary nitrogen (alkyldimonoim). The compositions can be used to disinfect or preserve contact lenses, as a rewet drop for contact lenses or to preserve pharmaceutical formulations. A particular ethoxylated glycoside described in U.S. Pat. No. 6,277,365 is of general formula

Glucoquat® 100 is available from Amerchol Corp, Edison, N.J. The compositions can also include a disinfectant such as poly(hexamethylene biguanide) and a therapeutic agent including dry eye agent such as hyaluronic acid or a drug for ophthalmic applications.